LED provides many advantages over conventional lighting features such as a higher efficiency, longer life span and less likely to be damaged, thus is widely used in people's daily life nowadays. However, due to the LED is driven by a front end DC power supply to generate light and the DC power supply outputs a high current in a constant current mode as shown in FIG. 6, the LED receives the high current continuously. As a result, aside from generating light, a great amount of heat also is generated. The heat is accumulated and could result in overheated and malfunction of the LED. The fluorescent powder used on white light LEDs also could be degraded under heat and result in change of light color. All this seriously affects the brightness and durability of the LED.
In order to disperse the heat of the LED when in use, the general approach is mounting an LED chip set onto a metal seat. The metal seat is connected to a radiation metal blade to disperse heat. However, when the LED is in a high current duty condition, heat dissipation efficiency often is not desirable and results in heat accumulation and forming hot spots. This could cause burned down of the LED. A conventional technique to attack this problem is installing radiation fins and even an air fan outside an LED module to provide more cooling power. As the power of LED increases constantly in recent years, the size of composite products also increases. The conventional technique mentioned above becomes a constraint to LED product design and production process. Improvements are needed to resolve those problems.